JPH06136466A - Treatment of molten aluminum or molten aluminum alloy - Google Patents

Abstract

(57) [Abstract] [Purpose] The present invention has no risk of explosion when vacuum-treating molten aluminum or molten aluminum alloy to remove contaminants in the molten metal, and also collects a metallic mass of the collected contaminants. The present invention provides a method for treating molten aluminum or molten aluminum alloy that can be reused. [Structure] The present invention is characterized by the following first step and second step. First step: The molten aluminum or the molten aluminum alloy is sucked into a vacuum tank through an ascending pipe while introducing an inert gas from the melting furnace or the holding furnace, and the molten metal is evaporated while the contaminants in the molten metal are evaporated in the vacuum tank. Refluxing through a downcomer. Second step: sucking the evaporated contaminant vapor together with an inert gas into a condenser, cooling and condensing the contaminant vapor in the condenser, and then heating the condensed contaminant to remelt it, A step of further solidifying and collecting as a metal lump.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for treating molten aluminum or molten aluminum alloy (hereinafter simply referred to as molten aluminum). Melting raw material scrap in a melting furnace, adjusting the molten aluminum melt in a holding furnace, when casting the adjusted aluminum melt into a predetermined shape in a casting machine, the aluminum melt is at least a stage before being provided to the casting machine, Treatment is performed to remove contaminants such as magnesium and zinc contained therein. The present invention relates to improvement of the method for treating such molten aluminum.

[0002]

2. Description of the Related Art Conventionally, as a method of treating molten aluminum, a method of sucking the molten aluminum together with an inert gas into a vacuum tank and evaporating contaminants in the molten aluminum in the vacuum tank (Japanese Patent Laid-Open No. 48-20709) Kaisho 57-134
242), a method of sucking the molten aluminum into a vacuum tank and evaporating contaminants in the molten aluminum while introducing an inert gas in the vacuum tank (JP-A-52-43708) and the like have been proposed. However, these conventional methods condense evaporated vapors of pollutants such as magnesium and zinc, and take out the condensed powdered pollutants into the atmosphere as they are, so that there is a risk of explosion at this time. There are drawbacks.

[0003]

The problem to be solved by the present invention is that, in the conventional method, there is a risk of explosion when the powdery substance of the contaminants evaporated and condensed from the molten aluminum is taken out.

[0004]

SUMMARY OF THE INVENTION The present invention, however, relates to a method for treating molten aluminum, which is characterized by the following first step and second step. First step: sucking the molten aluminum into the vacuum tank through the rising pipe while introducing an inert gas from the melting furnace or the holding furnace,
A step of refluxing the molten metal through a downcomer while evaporating contaminants in the molten metal in the vacuum tank. Second step: sucking the evaporated contaminant vapor together with an inert gas into a condenser, cooling and condensing the contaminant vapor in the condenser, and then heating the condensed contaminant to remelt it, A step of further solidifying and collecting as a metal lump.

In the present invention, the melting furnace or the holding furnace and the vacuum chamber are connected by the rising pipe and the descending pipe, and the inert gas is introduced into the rising pipe from the end on the melting furnace or holding furnace side or from the middle thereof. To do. The molten aluminum is sucked into a vacuum tank through an ascending pipe while introducing an inert gas from a melting furnace or a holding furnace, and the aluminum molten metal is evaporated through a descending pipe while evaporating contaminants in the molten aluminum in the vacuum tank. It is refluxed, and the contaminants in the molten aluminum are removed by evaporation by repeating such suction and reflux.

Further, according to the present invention, a vacuum pump is connected to the vacuum chamber through a condenser, the condenser is provided with a cooling means and a heating means, and the crucible can be removed from the lower end of the condenser. Install. The vaporized contaminant vapor is sucked into the condenser together with the inert gas, and the contaminant vapor is condensed by the cooling means in the condenser. Next, the condensed contaminants are re-melted by the heating means, and the re-melted contaminants are dropped into the crucible by their own weight. Then, the remelted material of the pollutant dropped by its own weight is solidified by spontaneous cooling, and the solidified metal mass of the pollutant is removed and recovered.

[0007]

According to the present invention, since the vapor of the contaminant evaporated from the molten aluminum is recovered as a metal block, there is no danger of explosion and the recovered metal block can be reused.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a system diagram schematically showing in cross section one embodiment of the present invention. The holding furnace 11 and the vacuum chamber 21 include a rising pipe 31.
And the downcomer 32. A preheating burner 22 is attached to the upper portion of the vacuum chamber 21, an inert gas introducing pipe 41 is connected to an intermediate portion of the rising pipe 31, and a lower end portion of the rising pipe 31 is a molten aluminum in the holding furnace 11. It is positioned below the molten metal surface of A.

A condenser 61 is connected to the downstream side of the vacuum chamber 21 via a valve 51. The condenser 61 is equipped with a water cooling serpentine tube 62 and a radiant tube 63,
A crucible 71 is removably attached to the lower end of the condenser 61. A dust remover 81 is connected to the downstream side of the condenser 61 via a valve 52, a vacuum pump 91 is connected to the downstream side of the dust remover 81, and a space between the condenser 61 and the valve 52. The inert gas introducing pipe 42 is connected via the valve 53.

In FIG. 1, the condenser 61 is provided with a water-cooled serpentine tube 62 as a cooling means, but this may be, for example, a water-cooled panel or a water-cooled jacket, and a radiant tube 63 is provided as a heating means. May be, for example, a sheath heater.

The vacuum chamber 21 is operated by operating the vacuum pump 91.
While maintaining the internal atmosphere of 0.5 Torr, an argon gas was introduced from the inert gas introduction pipe 41 to the riser pipe 31 at a rate of 100 liters / min, and the total amount of the molten aluminum A of 40 t loaded in the holding furnace 11 was changed. It was sucked into the vacuum chamber 21 together with argon gas through the rising pipe 31. The suctioned molten aluminum is preheated by the preheating burner 22 and the vacuum chamber 2
After performing the vacuum treatment in No. 1, it was refluxed to the holding furnace 11 through the downcomer pipe 32 at 20 t / min.

Contaminant vapor evaporated from the molten aluminum by vacuum treatment was sucked into a condenser 61 together with argon gas through a valve 51 and condensed in a water-cooled corrugated pipe 62. The exhaust gas after condensing the pollutant vapor was discharged into the atmosphere through the valve 52, the dust remover 81, and the vacuum pump 91.

After repeating suction for 30 minutes through the ascending pipe 31, vacuum treatment and reflux through the descending pipe 32 for 30 minutes, the valves 51 and 52 were closed and the vacuum pump 91 was stopped. Next, the valve 53 was opened, and argon gas was introduced into the condenser 61 to restore the internal pressure of the condenser 61. After discharging the cooling water from the water-cooled spiral tube 62, the condensed contaminants were heated to 650 ° C. in the radiant tube 63 and remelted. The remelted contaminant fell to the crucible 71 by its own weight. The heating by the radiant tube 63 was stopped, and the re-melted material of the pollutant dropped to the crucible 71 by its own weight was solidified by cooling. Then, the crucible 71 was removed from the condenser 61, and the solidified contaminated metal mass was collected.

[0014]

As is apparent from the above, according to the present invention described above, there is no danger of explosion when removing the contaminants in the molten aluminum by vacuum processing the molten aluminum, and the metal of the recovered contaminants is used. There is an effect that the lump can be reused.

[Brief description of drawings]

FIG. 1 is a system diagram schematically showing in cross section one embodiment of the present invention.

[Explanation of symbols]

11 ... Holding furnace, 21 ... Vacuum tank, 31 ... Upcomer pipe, 32 ... Downcomer pipe, 41, 42 ... Inert gas introduction pipe, 61 ... Condenser, 62 ...・ Water-cooled pipe, 63 ・
..Radiant tubes, 71 ... crucibles, 81 ...
・ Dust remover, 91 ... vacuum pump

Claims (1)

[Claims] 1. A method for treating molten aluminum or molten aluminum alloy, which comprises the following first step and second step. First step: The molten aluminum or the molten aluminum alloy is sucked into a vacuum tank through an ascending pipe while introducing an inert gas from the melting furnace or the holding furnace, and the molten metal is evaporated while the contaminants in the molten metal are evaporated in the vacuum tank. Refluxing through a downcomer. Second step: sucking the evaporated contaminant vapor together with an inert gas into a condenser, cooling and condensing the contaminant vapor in the condenser, and then heating the condensed contaminant to remelt it, A step of further solidifying and collecting as a metal lump.